Expose manifest file tags in the API output

[ChrisJr404]

Summary

Adds a tags field to each file in the --api JSON output, so consumers can tell which files are saves versus configs (and anything else the manifest tags). This is what #534 asked for.

The tags come straight from the manifest entries that matched a file, so a file gets save, config, etc. based on the paths it was found under. As mentioned in the issue, paths can overlap (for example a config directory that contains the save directory), so when more than one manifest entry resolves to the same file its tags are unioned rather than one winning. The field is omitted when empty, so existing output is unchanged and restore output (which has no manifest tags) is unaffected.

Implementation notes

• ScannedFile now carries the tags collected while scanning for backup.
• During the backup scan, tags from each manifest file entry are tracked per candidate path and attached to the files found under it, accumulating across overlapping paths.
• ApiFile exposes them as tags, skipped when empty.

I left the generated docs/schema files alone since regenerating them here also pulls in an unrelated schemars format bump, so that seems better left for a release.

Testing

• cargo test
• cargo fmt --all -- --check
• cargo clippy --workspace -- --deny warnings

Added can_scan_game_for_backup_with_tags covering a config file and a save directory.

Closes #534

[mtkennerly]

Thanks! This looks good 👍